Specifications

3 General Programming

3.6 Symbolic addressing

Programming Guideline for S7-1200/1500

V1.2, Entry ID: 81318674

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Figure 3-24: Retentive counter as multi-instance

NOTE

If the retentive memory on the PLC is not sufficient, it is possible to store data in

the form of data blocks that are only located in the load memory of the PLC. The

following entry is described by taking the example of an S7-1200. This

programming also works for S7-1500.

You will find further information in the following entry:

In STEP 7 V11, how do you configure data blocks with the "Only store in load

memory" attribute for an S7-1200?

http://support.automation.siemens.com/WW/view/en/53034113

3.6 Symbolic addressing

3.6.1 Symbolic instead of absolute addressing

The TIA Portal is optimized for symbolic programming. This results in many

advantages. Due to the symbolic addressing you can program without having to

pay attention to the internal data storage. The controller handles where the best

possible storage is for the data. You can therefore completely concentrate on the

solution for your application task.

Advantages

 Easier to read programs through symbolic tag names

 Automatic update of tag names at all usage locations in the user program

 Memory storage of the program data does not have to be manually managed

(absolute addressing)

 Powerful data access

 No manual optimization for performance or program size reasons required

 IntelliSense for fast symbol input

 Fewer program errors due to type checking (validity of data types is checked

for all accesses)